Thin film apparatus

ABSTRACT

A thin film apparatus of the type embodying an approximately vertical treatment compartment or chamber and with which merges at the upper end thereof a separation compartment possessing a rotor equipped with vanes or blades as well as two ring members which are spaced in axial direction from one another. The ring members surround the cross section of the separation compartment which is swept over by the rotor. Radially extending droplet collecting ridges, grooves or the like are provided at the aforementioned rotor blades or vanes, these droplet collecting ridges opening between both of the ring members. According to important aspects of the invention, the ring members are rigidly connected for rotation with the vane rotor and possess an internal diameter which essentially corresponds to the diameter of the rotor, and furthermore, the ring members partially bound the liquid-throughpassage means disposed externally of the rotor.

United States Patent Widmer et al. [451 July 25, 1972 [54] THIN FILM APPARATUS FOREIGN PATENTS OR APPLICATIONS [72] Inventors: Fritz Widmer, Fallanden; Janos Miklos 200,954 1/1966 Sweden ..159/6 W Gorbei, Zurich, both of Switzerland 36 ea 16 as Primary ExaminerNorman Yudkoff Assistant Examiner-J. Sofer Atmrne vWerner W. Kleeman 5 ABSTRACT A thin film apparatus of the type embodying an approximately vertical treatment compartment or chamber and with which merges at the upper end thereof a separation compartment possessing a rotor equipped with vanes or blades as well as two ring members which are spaced in axial direction from one another. The ring members surround the cross section of the separation compartment which is swept over by the rotor. Radially extending droplet collecting ridges, grooves or the like are provided at the aforementioned rotor blades or vanes, these droplet collecting ridges opening between both of the ring members. According to important aspects of the invention, the ring members are rigidly connected for rotation with the vane rotor and possess an internal diameter which essentially corresponds to the diameter of the rotor, and furthermore, the ring members partially bound the liquidthroughpassage means disposed externally of the rotor.

9 Claims, 4 Drawing Figures VAPOR mscmwoz 7? I 52 i 56 1F 56 so i 11 v 10 48 72 54 HEAT Tmmaftn iriE i 7 mtmummiu 22 zamtnrma JACKET) HEAT TRANSFER MEDIUM OUTLET 2O MATERIAL OUTLET Patented July 25, 1972 3,678,983

2 Sheets-Sheet 1 24 k 14/ 1 LL vAPoR DISCHARGE 10a 72/ \54. HEAT TRANSFER flEgl F MEDIUM INLET 2 (HEATING JACKET) HEAT TRA-s|=ER MEDIUM OUTLET L MATERIAL OUTLET INVENTORS ATTORNEY Patented July 25, 1972 3,678,983

2 Sheets-Sheet 2 INVENTORS Fklil MIJMEK sa vo;

ATTORNEY THIN FILM APPARATUS BACKGROUND OF THE INVENTION The present invention relates to a new and improved construction of thin film apparatus of the type comprising an approximately vertically disposed treatment compartment or chamber and a separation compartment or chamber which merges with the upper end of the treatment compartment, this separation chamber containing a rotor equipped with blades or vanes.

The prior art is already familiar with a thin film evaporator embodying a vertically disposed, rotationally symmetrical evaporation compartment. At the upper end of the evaporation compartment there merges a separation compartment. A shaft extends substantially coaxially with respect to said separation-and evaporation compartments. A number of suitable vanes or blade members are attached to this shaft and extend axially over the length of the separation compartment and the evaporation compartment, these blades also extending radially up to the region of the inner wall of the evaporation compartment.

An annular compartment is provided between the separation chamber or compartment wall and the rotor vane extremities, a substantially ring-shaped disc member being secured in this annular compartment to the separation chamber wall at the region of the vanes. In similar fashion a second substantially ring-shaped disk member is secured to the wall of the separation chamber directly above the upper ends of the vanes. Between these disk members there are secured to the inner separation chamber wall a number of axially extending vane portions which also extend radially up to the region of the rotor vanes. Furthermore, beneath the ringshaped disk member disposed at the inner wall of the separation chamber at the region of the rotor vanes there are arranged upon the rotor between the vane members thereof segments of a ring-shaped disk, the external diameter of which coincides with that of the rotor.

During operation of this type prior an thin film evaporator the vapors which are freed in the evaporation chamber ascend into the separation chamber and are deflected by the segments arranged at the rotor between the vanes in the direction towards the separation chamber wall. Accordingly, a first portion of the liquid droplets entrained by the vapors are separated at the underside of the ring segments and thrown by the centrifical forces prevailing during rotation of the rotor against the separator chamber wall. After the first deflection of the vapor stream, these liquid droplets impact against the ring disks secured to the separation chamber wall, by means of which they are again deflected towards the center of the rotor. In so doing, a further portion of the liquid droplets are separated from the vapor stream at the aforementioned ring disks. Hence, the vapor stream which has again penetrated into the region of the rotating vanes is freed by such from such liquid droplets, the vane members throwing the separated droplets onto the separator chamber walLT-he upper end of the vane or blade is provided with a ridge or depression, the

function of which is to collect the liquid droplets entrained by the vapor stream along the surface of the vane and to eject or propel such droplets thereafter onto the separation chamber wall. The vanes secured to the separation chamber wall between the two ring disk members have the function of acting upon the vapor currents departing from the region of the rotating vanes and which have imparted thereto a rotational movement and to deflect such vapor currents so as to partake in an axial directed movement in a direction towards the vapor discharge connection.

The separated droplets flow along the vapor chamber wall towards the evaporation chamber and are dammed up by the ring disks arranged at the separation chamber wall, from which location they can drop into the evaporation compartment.

A major drawback of this type droplet separator is the fact that the separated droplets which are to be returned into the evaporation chamber must penetrate through the ascending vapor current a number of times approximately at right angles. Hence, it is impossible to prevent the vapors which are flowing towards the vapor discharge connection from at least partially again entraining the downwardly falling droplets. Hence, the upperwardly directed vapor stream tends to remove these entrained droplets from the operable region of the droplet separator, and consequently, the withdrawn vapors are charged with particles of the material to be treated. This liquid component must then be either removed externally of the thin film apparatus by a separator from the vapors, or it can be conveyed away together with the vapors. In each situation, there cannot be avoided a more expensive processing of the material which is to be concentrated through the action of the thin film apparatus, because the efficiency of the thin film apparatus is reduced, or however, there must be taken into account a considerable loss of otherwise useful material.

SUMMARY OF THE INVENTION Accordingly, there is a real need in the art for an improved thin film apparatus which effectively overcomes the aforementioned drawbacks of the prior art constructions as explained above. It is a primary object of this invention to provide just such type of improved thin film apparatus which effectively fulfills this need and capably overcomes the aforementioned drawbacks associated with the prior art structures.

Another noteworthy object of the present invention is to provide an improved thin film apparatus which provides for more economical material processing.

Still a further significant object of the present invention relates to an improved thin film apparatus which substantially minimizes the loss of droplets of the material being treated by minimizing entrainment thereof by the vapor stream departing from the system.

Still a further noteworthy object of the present invention relates to an improved thin film apparatus for the treatment of materials which is relatively simple in construction, extremely economical to manufacture, provides for improved economy in the treatment operation, is not readily subject to breakdown, and is easy to service.

The invention is predicated upon the recognition that in order to achieve a good efficiency of the separator it is less important to attain a practically complete first separation of all liquid droplets through multiple deflection of the vapor-or gas stream, which can be associated with considerably pressure losses; rather it is more important to prevent the separated liquid from again being entrained by the vapor-or gas stream.

Hence, in order to achieve this objective, as well as to obtain the aforementioned objects of the invention as specified above, the invention contemplates a thin film apparatus construction wherein the ring members are rigidly connected for rotation with the rotor equipped with blades or vanes, and furthermore, that such ring members possess an internal diameter which is approximately equal to the diameter of the rotor, and further, wherein such ring members partially bound the liquid-throughpassages or openings situated externally of the rotor construction.

Due to the aforementioned bounding or delimiting of the annular compartment disposed radially outside of the rotor vanes by the rotating ring-disk members, there is attained the noteworthy advantage that these ring members also eject the separated liquid droplets against the wall of the separation compartment or chamber. The collecting droplets can then flow along this wall at a location which is radially outside of the ascending vapor-or gas stream. Furthermore, these droplets collecting at the separator wall can then flow through the throughpassages or openings back into the treatment compartment. In any event, there is no longer any crossing or intersection between the flow paths of the vapor-or gas stream and the separated liquid droplets once these droplets have reached the wall of the treatment compartment.

Experiments have shown that the invention arrangement and construction of thin film apparatus provides a surprisingly high separation effect.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detained description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is an elevational sectional view of a preferred embodiment of inventive thin film evaporator equipped with a droplet separator;

FIG. 2 is a cross-sectional view of the thin film evaporator depicted in FIG. 1, taken substantially along the line Illl thereof;

FIG. 3 is an enlarged fragmentary view of a modified construction of droplet separator for use in the thin film evaporator construction of FIG. 1; and

FIG. 4 is a similar enlarged fragmentary view of a still further variant construction of droplet separator for use in the thin film evaporator structure of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in FIGS. 1 and 2 reference numeral generally designates an approximately vertically arranged, rotationally symmetrical thin film evaporator embodying a housing 100 which is subdivided into a lower evaporation compartment or chamber 12 and a vapor compartment or chamber 14 arranged above this evaporation chamber 12. The vapor compartment 14 defines an axial extension of the evaporation chamber 12. The upper end of the vapor compartment or chamber 14 is sealed by a cover member 16, while the lower end of the evaporation compartment 12 is sealed by a conical member 18 which, in turn, opens into a discharge or outlet connection 20. In the illustrated exemplary embodiment of thin film apparatus, there is provided a suitable heating jacket 26 which encloses the confines of the evaporation chamber 12. A material inlet opening or connection 22 is provided at the region of the vapor compartment 14 at the wall of the evaporation compartment or chamber 12. Further more, the wall of the vapor compartment 14 is equipped with a vapor discharge conduit 24 directly below the cover member 16.

A rotor construction, generally designated by reference character 32, is arranged coaxially with respect of the vapor compartment 14 and the evaporation compartment 12. This rotor means or construction 32 will be seen to embody a central tubular body 34, the upper end of which is equipped with a shaft stub or journal 36 and by means of this journal is rotatably mounted at a suitable bearing 38 provided at the cover member 16. The lower end of this tubular body or shaft 34 likewise has a shaft stub or journal 40 which is supported in a bearing 42. Bearing 42, in turn, is retained by a plurality of supports 44 mounted coaxially within the conical portion 18.

Now at the region of the evaporation chamber 12 there are arranged at the tubular body or shaft 34 a number or axially extending wiper vanes or blades 46 which also extend radially up to the region of the inner wall of the evaporation chamber 12.

Continuing, it will be recognized that directly beneath the vapor discharge conduit 24 there is arranged at the tubular body or shaft 34 a droplet separator construction, generally designated by reference character 48. This droplet separator 48 embodies a plurality of droplet separator blades or vanes 50 which extend axially between the evaporation chamber 12 and the vapor discharge conduit 24. Separator vanes 50 also extend radially towards the inner wall of the associated vapor compartment or chamber 14 and terminate at a spacing therefrom. The star-shaped configuration of these separator vanes 50 which are arranged at the tubular body or shaft 34 are surrounded at their upper and lower ends by a respective substantially ring-shaped disk member 52 and 54. These ringshaped disk members 52 and 54, respectively, partially delimit or bound in axial direction the free space appearing between the wall of the vapor chamber 14 and the separator vanes or blades 50. Furthermore, it is also possible, depending upon the axial extent of the droplet separator 48, to provide over the length of the separator vanes 50 more than two such ringshaped disk members which, for instance, are arranged at an equal spacing from one another. Furthermore, viewed in the direction of rotation of the rotor 32, there are arranged at the front side or face of the separator vanes or blades 50 at an axial spacing from one another a plurality of droplet collecting ridges or depressions 56 which extend radially along the entire width of each associated separator vane 50. The rotor 32 is connected in driving relationship via the shaft stub 36 with a suitable drive motor 58 or any other suitable prime mover.

During operation of the invention herein disclosed thin film evaporator 10 the material which is to be concentrated is introduced through the inlet connection 22 into the evaporation compartment 12 heated by the heating jacket 26. The wiper blades 46 rotating within the evaporation compartment 12 distribute the material to be concentrated in the form of a thin film onto the inner wall of the evaporation compartment 12. Due to the action of gravity the thin film of material tends to flow towards the discharge or outlet connection 20. The vapors, resulting from concentration of the material, flow in counter current to the aforementioned thin layer or film, towards the vapor chamber or compartment 14, where they are conducted through the droplet separator unit 48. After material droplets have been removed from the vapors, the thus cleaned vapors are guided through the vapor discharge connection 24 to a nonillustrated condensor or other suitable piece of equipment, where they are condensed.

The vapor streams charged with droplets, and flowing towards the droplet separator 48, are deflected upon entry into such droplet separator, by the lower ring-shaped disk member 54 towards the center of the rotor unit 32. The vapor current deflected at the region of the separator vanes 50 is engaged by these separator vanes 50, so that through the action of the centrifical forces the heavier droplets are separated at the vanes. The vapors which flow through the droplet separator 48 have the tendency of entraining towards the vapor discharge connection 24 the droplets which have been separated out at the separator vanes or blades 50, However, to avoid or minimize such activity, the droplets, which have been collected by the collecting ridges 56 arranged at the front side of the separator vanes 50 in the direction of rotation of the rotor 32, are ejected by the action of the centrifical forces against the inner wall of the vapor compartment 14.

After passing through the annular or ring-shaped disk member 54 the vapor streams again expand. In so doing, the vapors impact against the second ring-shaped disk member 52 arranged at the upper end of the separator vanes 50, such ringshaped disk member 52 again deflecting the vapors towards the center of the rotor. Accordingly, a damming effect prevails between both of the annular disk members 52 and 54 at the space which is partially bounded by the inner wall of the vapor compartment 14 and the separator vanes 50, such damming action occurring in such a fashion that the droplets separated at the inner wall of the vapor compartment 14 are no longer entrained by the vapor streams flowing towards the vapor discharge connection 24. Furthermore, the radially directed vapor currents which exist by virtue of the rotation of the separator vanes or blades 50 flow through the axially directed currents which might still exist at the region of the free space between the inner wall of the vapor compartment 14 and the separator vanes 50.

However, the vapor streams flowing through the annular gap or throughpassage 72 existing between the inner wall of the vapor compartment 14 and the ring-shaped disk 52 have lost so much energy by virtue of the previously mentioned flow action of the radially directed vapor streams, that the remaining axially directed currents can no longer entrain the droplets separated out at the inner wall of the vapor compartment 14 in a direction towards the vapor discharge connection 24. Hence, substantially all of the droplets separated out at the inner wall of the vapor compartment 14 at the region of the droplet separator 48 are thus not subjected to the movement pulses of the vapor streams directed towards the vapor discharge connection 24. The separated droplets flow under the action of gravity through the annular gap or throughpassage 72 formed between the ring-shaped disk member 54 and the inner wall of the vapor compartment 14 back, in countercurrent flow with respect to the vapors, into the evaporation compartment 12 where they can again admix with the new incoming material entering into the evaporation compartment 12 via the inlet connection or stud 22.

By virtue of the previously described construction of the droplet separator unit 48, it is now possible to completely reclaim the liquid droplets entrained by the vapor currents, which not only enables dispensing with the use of a special separator outside of the thin film evaporator, rather also permits achieving an improved efficiency or degree of operation of the thin film evaporator. This is particularly then advantageous if expensive or relatively expensive materials are to be concentrated in the thin film evaporator.

FIG. 3 depicts a modified construction of droplet separator 48. A plurality of separator vanes 50 are again arranged at the tubular body or shaft 34, each such vane or blade being equipped with two different types of droplet collecting ridges 66 and 68 respectively. While the droplet collecting ridges 66 are formed as recesses or depressions at the front face of the rotating separator vanes or blades 50, the other droplet collecting ridges 68 are constructed in the form of ledges disposed at the front face of each rotating separator vane 50. Furthermore, the side of each ledge member 68 facing towards the evaporation compartment is equipped with a depression or ridge 70 which ensures for an improved withdrawal of the collected droplets.

Furthermore, the separator construction shown in this embodiment will be seen to have the ring-shaped disk members 60 and 60' which are arranged at the axial ends of the separator vanes 50 slotted at their periphery at least at one location, so that the thus formed marginal portions 62, 64 of the slotted location overlap one another, as shown. These overlapping marginal portions 62, 64 of the annular or ring-shaped disks 60, 60 are flexed out of their plane in such a manner that they form a channel which is inclined in the direction of rotation of the droplet separator unit 48, with the inlet opening of such channel being disposed above the corresponding ring-shaped disk member 60 or 60 respectively. Whereas the bent marginal portion 62 of the disk member 60 which extends upwardly at an inclination has the function of engaging the droplets collected directly above the corresponding ringshaped disk member 60 and to convey such below such ringshaped disk member, the inclined downwardly flexed marginal portion 64 of the ring-shaped disk member 60 has the function of imparting a movement component directed towards the evaporator compartment 12 to the droplets collected at the region of such marginal portion 64. In similar fashion the lower ring-shaped disk member 60 is equipped with at least one such analogous opening or channel, whereby the function of this opening corresponds to that of the channel or opening described with respect to the ring-shaped disk member 60. By virtue of this design of droplet separator 48 there is achieved that, apart from the gravitational forces which act upon the droplets, there is imparted particularly to the droplets collecting below the ring-shaped disk members 60 an additional component of movement so that there is achieved an improved return of the separated droplets.

In the arrangement of separator unit depicted in FIG. 4, the separator vanes or blades 74 are twice flexed or bent and form, as viewed in the axial extent of the droplet separator 48, a substantially zig-zag line. The arrangement of separator vane 74 increases the separation effect of the droplet separator 48,

which additionally is further supported by the collecting ridges or rills 76 arranged at the separator vanes 74. Furthermore,

between the upper and lower ring-shaped disk members 78 and 78' there is arranged at least one spiral 80, the radial extent of which corresponds to that of the ring-shaped disk members 78 and 78, respectively, and the pitch of which can be determined in accordance with the prevailing requirements. By virtue of the arrangement of a spiral 80 or similar member between both ring-shaped disk members 78 and 78 there is achieved a markedly improved return of the droplets separated at the inner wall of the vapor compartment 14 at the region of the droplet separator unit 48. Furthermore, with this construction it is important that the spiral 80 extends up to the direct region of the inner wall of the vapor compartment 14 in order to thus optimumly engage the separated liquid particles and to impart to such a component of movement which is directed towards the evaporation chamber 12. The arrangement of a spiral 80 between the two ring-shaped disk members 78 and 78' furthermore has the advantage that the vapor rotating between the droplet separator 48 and the inner wall of the treatment chamber or compartment 14 has imparted to it a component of movement which is directed towards the evaporation compartment 12. It has been found that the droplet separator 48 possesses a greater rotational velocity than the vapor cushion between such droplet separator 48 and the inner wall of the vapor compartment 14, which, in turn, renders it possible to impart to the previously mentioned vapor cushion a component of movement which is directed in countercurrent to the vapors. Consequently, conditions can be obtained in the annular compartment which is partially bounded by the ring-shaped disk members 78 and 78' which ensure for an approximately percent return of the separated droplets.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,

What is claimed is:

l. A thin film apparatus comprising means providing a substantially vertically arranged material-treatment compartment which merges at its upper end with a droplet-separation compartment, rotor means equipped with blades provided for said separation compartment, at least two axially spaced ring members rigidly connected for rotation with said rotor means, said ring members encircling the cross-section of the separation compartment swept by said rotor means, substantially radially extending droplet collecting ridge means provided for said rotor blades and which open between said ring members, said ring members possessing an internal diameter which substantially corresponds to the diameter of said rotor means, said ring members partially limiting liquid-throughpassage means situated externally of said rotor means.

2. A thin film apparatus as defined in claim 1, wherein said droplet collecting ridge means are defined by depressions provided at the front face of each of said rotor blades defining separator vanes.

3. A thin film apparatus as defined in claim 1, wherein said droplet collecting ridge means are defined by at least one extended member at each associated blade protruding from the front face of said blade and equipped with at least one collecting ridge arranged at the side of said extended member facing said treatment compartment.

4. A thin film apparatus as defined in claim 3, wherein each extended member is defined by a ledge means.

5. A thin film apparatus as defined in claim 1, further including at least one spiral means for interconnecting both of said ring members.

6. A thin film apparatus as defined in claim 1, wherein each ring member is provided at its periphery with at least one cutout portion extending over the entire width of said ring member.

9. A thin film apparatus as defined in claim 1, further including a rotor provided with rotor vanes arranged in said treatment compartment, said rotor blades of said rotor means of said separation compartment being separate from said rotor vanes of said rotor of said treatment compartment. 

1. A thin film apparatus comprising means providing a substantially vertically arranged material-treatment compartment which merges at its upper end with a droplet-separation compartment, rotor means equipped with blades provided for said separation compartment, at least two axially spaced ring members rigidly connected for rotation with said rotor means, said ring members encircling the cross-section of the separation compartment swept by said rotor means, substantially radially extending droplet collecting ridge means provided for said rotor blades and which open between said ring members, said ring members possessing an internal diameter which substantially corresponds to the diameter of said rotor means, said ring members partially limiting liquid-throughpassage means situated externally of said rotor means.
 2. A thin film apparatus as defined in claim 1, wherein said droplet collecting ridge means are defined by depressions provided at the front face of each of said rotor blades defining separator vanes.
 3. A thin film apparatus as defined in claim 1, wherein said droplet collecting ridge means are defined by at least one extended member at each associated blade protruding from the front face of said blade and equipped with at least one collecting ridge arranged at the side of said extended member facing said treatment compartment.
 4. A thin film apparatus as defined in claim 3, wherein each extended member is defined by a ledge means.
 5. A thin film apparatus as defined in claim 1, further including at least one spiral means for interconnecting both of said ring members.
 6. A thin film apparatus as defined in claim 1, wherein each ring member is provided at its periphery with at least one cutout portion extending over the entire width of said ring member.
 7. A thin film apparatus as defined in claim 6, wherein said cutout portion of each ring member is defined by overlapping marginal portions.
 8. A thin film apparatus as defined in claim 7, wherein said overlapping marginal portions form therebetween a channel which is inclined in the direction of rotation of said rotor means.
 9. A thin film apparatus as defined in claim 1, further including a rotor provided with rotor vanes arranged in said treatment compartment, said rotor blades of said rotor means of said separation compartment being separate from said rotor vanes of said rotor of said treatment compartment. 